The present relates, in general, to watthour meter sockets and watthour meter socket adapters and, more specifically, to watthour meter socket and socket adapter jaws contacts.
In the electric utility industry, plug-in, socket-type watthour meters are commonly employed to measure electrical power consumption at a residential or commercial building establishment. A cabinet is typically mounted on an outside wall of the residence or building and contains a meter socket having pairs of line and load contacts which are connected to electric power line conductors extending from the utility power network and electric load conductors connected to the residential or building establishment power distribution network. The contacts receive blade terminals on a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals mounted in the cabinet for the measurement of electrical power consumption.
S-type, socket-type, plug-in watthour meters have replaced older A base bottom connected meters which were formed of a single piece housing in which the watthour meter was fixedly mounted along with compression terminals which provide connection to the utility power lines and the building load distribution network.
In an installation involving an A-type bottom connected meter, an A to S socket adapter is used to allow a new S-type watthour meter to be installed. The socket type meter has outwardly extending blade terminals which are insertable into the jaw contacts in the cabinet of an S-type meter socket. The socket adapter includes its own set of female jaw contacts which receive the male blade terminals of the S-type plug-in, socket-type meter.
The jaw contacts employed in the watthour meter socket and watthour meter socket adapter may take many different forms including a folded over contact structure as well as a blade and spring clip structure. Regardless of the structural arrangement of the jaw contact, each jaw contact in a watthour meter socket adapter or watthour meter socket must provide a secure electrical connection to a blade terminal inserted therein as well as enabling the blade terminal to be both easily inserted into and removed from the jaw contact to function with a plug-in watthour meter or watthour meter socket adapter.
Thus, jaw contacts are designed to meet certain minimum push-in and pull-out force requirements, such as twenty-five pound push-in force and a seven and one half pound pull-out force. These force requirements enable a jaw contact in a watthour meter socket or watthour meter socket adapter to meet the dual functions of easy insertion and replacement of a watthour meter or socket adapter and providing a secure electrical connection to the blade terminal inserted therein over the typically long service life of a watthour meter socket or watthour meter socket adapter. However, there is no known tester for jaw contacts used in a watthour meter socket adapter or watthour meter socket which is capable of measuring the push-in and/or pull-out forces generated by a jaw contact on a blade terminal.
Despite the fact that there has been no known tester for jaw contacts to measure the push-in or pull-out forces generated by a jaw contact on a blade terminal, it is known that the push-in and pull-out forces vary practically from jaw contact to jaw contact despite tight manufacturing process controls. It would be desirable to have a jaw contact conditioner which can be easily inserted into a jaw contact, typically after the jaw contact is mounted in a watthour meter socket or socket adapter/extender, and pushed into and pulled out of the jaw contact several times to condition the jaw contact for the insertion of a meter blade terminal therein by relaxing or opening the jaw contact jaws a minute amount to thereby bring the push-in forces closer to specifications.
The Assignee of the present invention has previously employed a standard jaw blade terminal fixed, such as by welding, on the end of a long handle-like screwdriver as a jaw conditioner. However, it is believed that further improvements may be made to a jaw contact conditioner to adapt the conditioner to also function as a blade terminal/jaw contact push-in and pull-out force measurement device.
The present invention is a jaw contact tester and jaw contact conditioner useful in measuring blade terminal push-in and pull-out forces relative to a jaw contact mountable in an electrical power service apparatus. In a first aspect of the present invention, a jaw contact tester apparatus is disclosed for testing the pull-out force of a jaw contact in an electrical device, such as a watthour meter socket or a watthour meter socket adapter. The tester comprises a housing having first and second opposed ends, with the first end is displaceable relative to the second end. A blade is fixedly mounted within the housing and is extendable through the first end of the housing into relatable engagement with the jaw contact upon engagement of the first end of the housing with the jaw contact. Biasing means are disposed in the housing for exerting a force between the first and second ends of the housing tending to separate the blade from a jaw contact when the blade is mounted in a jaw contact. The biasing means will cause the blade to disengage from the jaw contact only when the force exerted by the biasing means on the housing engaged with the jaw contact exceeds the pull-out force resistance of the jaw contact on the blade.
In this aspect, the housing preferably includes a first housing portion and a second housing portion, the first housing portion being telescoping arranged relative to the second housing portion. A slot is formed in the first end of the first housing portion for slidable extension of the blade therethrough. The biasing means is disposed between the first end of the first housing and a support mounted within the first and second housing portions and fixedly connected to the second housing.
In another aspect, the jaw contact tester includes a housing having an aperture at one end. A slider is movably disposed within the housing and has an end formed as a blade terminal slidingly extendible through the aperture in the housing into releasable engagement with a jaw contact in an electrical apparatus. A first plunger is carried by the slider for movement in one direction and displaceable from the slider upon movement of the slider in an opposite direction. Biasing means are coupled to the slider for biasing the slider in a direction to retract the first end of the slider toward the housing. A first indicator is carried by the first plunger and extends through an aperture in the housing adjacent to a scale means on the housing for indicating the force required to move the blade terminal relative to the jaw contact.
A second plunger may also be mounted from the housing. A second indicator is carried by the second plunger and extends through a second aperture in the housing for displacement relative to a second scale means carried on the housing. The second plunger is operable by movement of the slider in an opposite direction.
The first and second plungers are separable from the slider upon movement of the slider in opposite directions.
In another aspect of the invention, jaw contact tester is in the form of a blade holder having a blade mountable on and extending from one end of the holder. Means are formed on the second end of the holder for receiving a coupler attachable to a force measurement device, such as a force measurement gauge. In one aspect, an open ended slot is formed at the other end of the holder body and receives a transversely mounted pin. A hook is attachable to the force measurement device and the pin to measure blade pull-out force relative to a fixed jaw contact.
In another aspect, a threaded coupler is attachable to the force measurement device and is threadingly engagable in a threaded bore formed in the other end of the holder body to attach the force measurement device to measure at least one of, and preferably, both of the blade push-in and blade pull-out forces relative to a stationery jaw contact.
The jaw contact testers and conditioners of the present invention provide a unique means for measuring blade push-in and/or pull-out forces relative to a stationary jaw contact mountable in an electrical power service apparatus, such as a watthour meter or watthour meter socket adapter/extender.
The jaw contact testers may be constructed in different versions to provide a simple go/no-go blade pull-out force test. Alternately, the blade holder itself may be provided with force measurement scales to provide an indication of one or both of blade push-in and blade pull-out forces. Further, a force measurement device, such as a force gauge, is attachable to the blade holder to measure blade push-in and pull-out forces.